1. Field of the Invention
The present invention relates to a method of and apparatus for cleaning a sheet-like substrate (referred to hereinafter as a "substrate") such as a semiconductor substrate or a glass substrate for liquid crystal display while rotating the substrate.
2. Description of the Background Art
In general, the substrate is sequentially subjected to various processes such as resist coating, exposure, and development for desired substrate processing. Since contamination by particles and the like deposited on the substrate during the above described processes results in significantly deteriorated characteristics of the processed substrate, the substrate cleaning apparatus cleans the substrate using various cleaning means such as a cleaning brush, an ultrasonic cleaning nozzle, a high-pressure cleaning nozzle or a cleaning chemical dispensing nozzle.
Each of the various cleaning means is provided on the forward end of an arm having a pivot axis outside a rotary table for placing and rotating the substrate thereon. By the pivotal movement of the arm, the cleaning means are retracted externally to of the rotary table so as not to interfere with loading or unloading the substrate before and after the cleaning process, and are positioned over a surface of the substrate during the cleaning process.
The cleaning brush, during the cleaning process, is positioned in contact with or in slightly spaced relation with the substrate, and is driven from the center of rotation of the substrate toward the periphery thereof to sweep away the particles on the substrate surface.
The ultrasonic cleaning nozzle, and high-pressure cleaning nozzle during the cleaning process, are driven so that a cleaning fluid delivered therefrom reaches locations on the substrate surface in a reciprocal manner between the center of rotation of the substrate and the periphery thereof, and function to peel off the particles deposited on the substrate. The peeled particles are removed by centrifugal force caused by the rotation of the substrate.
To clean the substrate more positively, there has been used a substrate cleaning apparatus comprising the plurality of above described cleaning means. Such a substrate cleaning apparatus is designed such that the plurality of cleaning means sequentially move toward positions over the substrate to clean the substrate.
However, the substrate cleaning apparatus wherein one of the cleaning means performs the cleaning process while the other cleaning means are retracted externally to of the rotary table in a repeated manner requires prolonged cleaning time, resulting in low processing efficiency.